The metadata below describe the original scanning. Follow the "All Files: HTTP" link in the "View the book" box to the left to find XML files that contain more metadata about the original images and the derived formats (OCR results, PDF etc.). See also the What is the directory structure for the texts? FAQ for information about file content and naming conventions.
"This is, so far as known to me, the only attempt to set out, from an architect's point of view, the basis of certain ideas common in the architecture of many lands and religions, the purposes behind structure and form which may be called the esoteric principles of architecture."